Vacuum-assisted fixation apparatus

Abstract

A stereotactic fixation apparatus provides for accurate and reproducible positioning of a patient's skull during medical diagnostic and treatment procedures. The stereotactic fixation apparatus includes a mouthpiece having a bite block formed as an impression of the patient's upper teeth and hard palate. The mouthpiece is connected to a stereotactic frame, which in turn is releasable connected to an adaptor board on which the patient rests. Vacuum pressure is used to draw the bite block firmly against the patient's hard palate. Vacuum pressure is also used to hold the stereotactic frame on the adaptor board. The stereotactic fixation apparatus additionally includes a patient-activated safety release mechanism which allows the patient to disconnect the vacuum pressure and to dislodge the restraints of the mouthpiece and frame, as well as to disable the medical equipment used with the medical diagnostic or treatment procedure.

What is claimed is: 
     
       1. A stereotactic fixation apparatus, comprising: a stereotactic frame; and   a mouthpiece attached to said stereotactic frame, said mouthpiece having a surface for contacting a patient's hard palate and a port positioned at a point on said mouthpiece distal of said surface and adapted for connection to a source of vacuum, said mouthpiece being configured to provide a fluidic path between said surface and said port to provide a vacuum attachment between the surface and the hard palate of the patient.   
     
     
       2. The stereotactic fixation apparatus of claim 1 additionally comprising a vacuum control system configured to communicate with the source of vacuum so as to regulate vacuum from said source of vacuum and a remote patient-activated switch which communicates with said vacuum control system for terminating vacuum pressure in the fluidic path defined by said mouthpiece. 
     
     
       3. The stereotactic fixation apparatus of claim 1, wherein said surface is shaped to conform to the hard palate of the patient. 
     
     
       4. The stereotactic fixation apparatus of claim 3, additionally comprising a normally closed, one-directional flow valve in communication with the fluidic path provided between said surface and said port of said mouthpiece. 
     
     
       5. The stereotactic fixation apparatus of claim 4, wherein said surface has at least one hole which communicates with said port, said normally closed, one-directional flow valve being in said fluidic path between said hole in said surface and said port. 
     
     
       6. The stereotactic fixation apparatus of claim 5, wherein said hole in said surface opens into a normally sealed cavity formed within said valve, said cavity having a volume significantly less than the volume of said fluidic path of said mouthpiece. 
     
     
       7. The stereotactic fixation apparatus of claim 1 additionally comprising a coupling which connects said mouthpiece to said stereotactic frame, said coupling configured to provide at least three degrees of rotational movement of said mouthpiece relative to said stereotactic frame, and at least two degrees of linear movement of said mouthpiece relative to said stereotactic frame. 
     
     
       8. The stereotactic fixation apparatus of claim 7, wherein said coupling is removably attached to said stereotactic frame. 
     
     
       9. The stereotactic fixation apparatus of claim 7, wherein said coupling includes a locking mechanism which prevents said mouthpiece from moving in reference to said stereotactic frame and which permits said mouthpiece to be repositioned in exactly the same manner to said stereotactic frame. 
     
     
       10. The stereotactic fixation apparatus of claim 9, wherein said coupling comprises: a plurality of discs having a central bore formed through the center of the discs along a common axis, a first of said discs having a first bore positioned generally normal to said central bore and being positioned in said first disc so as not to intersect with said central bore, a second of said discs having at least a portion of a second bore positioned generally normal to said central bore and being positioned in said second disc so as not to intersect with said central bore;   a fastener having a shaft which passes through said central bore to join said discs together, said fastener having a first unlocked position in which said first and second discs are rotatable about said fastener shaft, and a second locked position in which said first and second discs are nonrotatable about said fastener shaft;   a substantially rigid member extending through said first bore of said first disc, said member and said first disc being adapted to permit said member to rotate about a vertical axis of said member when said fastener is in said unlocked position, and to prevent said member from rotating about said vertical axis of said member when said fastener is in said locked position, said member being connected to said port of said mouthpiece; and   a rod adapted to attach to said stereotactic frame, said rod extending through said second bore of said second disc, said rod and said second disc being adapted to permit said second disc to rotate about a longitudinal axis of said rod when said fastener is in said unlocked position, and to prevent said second disc from rotating about said longitudinal axis of said rod when said fastener is in said locked position.   
     
     
       11. The stereotactic fixation apparatus of claim 10, wherein said first bore breaks through a flat lateral surface of said first disc to an extent that no more than an arc length of 30° of an exterior surface of said rigid member extends beyond said flat lateral surface of said first disc with said rigid member extending through said first bore. 
     
     
       12. The stereotactic fixation apparatus of claim 10, wherein said second bore passes through an interface between said second disc and a third disc, a portion of said second bore extending into said third disc. 
     
     
       13. The stereotactic fixation apparatus of claim 10, wherein said rigid member is connected to a source of vacuum. 
     
     
       14. The stereotactic fixation apparatus of claim 1, wherein said mouthpiece comprises an impression of the patient's upper teeth and hard palate. 
     
     
       15. The stereotactic fixation apparatus of claim 14, wherein said mouthpiece additionally comprises a tray onto which said impression is mounted. 
     
     
       16. The stereotactic fixation apparatus of claim 1 additionally comprising a vacuum control system having a remote patient-activated switch which is configured to be held by a patient and which communicates with and controls a valve that is positioned in fluidic communication with said mouthpiece. 
     
     
       17. A fixation apparatus, comprising: a platform for supporting a body of a patient;   a skull immobilization device contacting said platform at least at one interface region; and   a port adapted for connection to a source of vacuum, said port being in fluidic communication with said interface region and formed in said platform or in said skull immobilization device whereby a vacuum holds said immobilization device against said platform when vacuum pressure is applied to said interface region through said port.   
     
     
       18. The fixation apparatus of claim 17, wherein said immobilization device comprises a stereotactic frame. 
     
     
       19. The fixation apparatus of claim 18, wherein said stereotactic frame has at least two footings which contact said platform at two interface regions, each of said interface regions including a cavity that is in fluidic communication with said port. 
     
     
       20. The fixation apparatus of claim 19, wherein at least one of said cavities is formed in one of said footings 
     
     
       21. The fixation apparatus of claim 19, wherein said at least one of said cavities is formed in said platform. 
     
     
       22. The fixation apparatus of claim 19, further comprising at each of said interface regions an O-ring compressed between said platform and each corresponding footing for forming a seal around each of said cavities. 
     
     
       23. The fixation apparatus of claim 22, wherein at least one of said O-rings is seated in a groove formed in said platform. 
     
     
       24. The fixation apparatus of claim 23 additionally comprising means for positioning at least one of said footings, on said platform such that said corresponding O-ring surrounds the periphery of said corresponding cavity. 
     
     
       25. The fixation apparatus of claim 17 additionally comprising a vacuum control system for communicating with at least the source of vacuum which communicates with at least said port so as to enable or disable the source of vacuum applied to said port, said vacuum control system having a remote patient-activated switch which is configured to be held by said patient and which communicates with said vacuum control system such that said vacuum control system disables the application of vacuum at said port when said patient activates said switch. 
     
     
       26. The fixation apparatus of claim 25, wherein said vacuum control system includes a solenoid valve configured to be positioned between and in fluidic communication with the source of vacuum and said port, said vacuum control system operating said valve in response to said patient-activated switch. 
     
     
       27. The fixation apparatus of claim 17, wherein said stereotactic immobilization device comprises a rigid face mask mounted to a frame, said face mask adapted to have shape which conforms to the contours of the anterior features of the patient's skull. 
     
     
       28. The fixation apparatus of claim 27, wherein said interface region comprises a cavity. 
     
     
       29. The fixation apparatus of claim 28, wherein said cavity is formed in said platform. 
     
     
       30. A method of accurately and reproducibly positioning a patient's skull for a medical procedure, said method comprising the steps of: providing a mouthpiece attached to a stereotactic frame;   positioning said mouthpiece within said patient's mouth in a position in which said mouthpiece extends beneath the patient's hard palate; and   applying a vacuum to draw said mouthpiece against the patient's hard palate so as to secure said mouthpiece within the patient's mouth.   
     
     
       31. The method of claim 30 additionally comprising the steps of: making an impression of the patient's upper teeth and hard palate; and   mounting said impression on a tray to form said mouthpiece.   
     
     
       32. The method of claim 31, wherein said step of applying a vacuum comprises drawing a vacuum between said impression and the patient's hard palate so as to draw said impression firmly against the patient's hard palate. 
     
     
       33. The method of claim 30 additionally comprising the steps of: providing a coupling between said mouthpiece and said stereotactic frame, said coupling providing three degrees of rotational freedom and two degrees of axial freedom in of to said mouthpiece relative to said stereotactic frame;   adjusting the position of the patient's head to a set position with said mouthpiece secured within the patient's mouth; and   locking said coupling with said mouthpiece in said set position to prevent the coupling from rotating or moving axially in reference to said stereotactic frame.   
     
     
       34. The method of claim 33 additionally comprising the step of removing said coupling from said stereotactic frame with said mouthpiece remaining attached to said coupling. 
     
     
       35. The method defined in claim 30, wherein said step of providing a mouthpiece comprises: making a dental impression of a patient's teeth using a first material;   making a study cast of said patient's teeth using said dental impression;   making an impression of said study cast using a second material different from said first material to provide a bite block; and   forming a passageway through said mouthpiece to provide a path for drawing said mouthpiece against the interior of the patient's mouth.   
     
     
       36. The method defined in claim 35 additionally comprising the step of providing a normally closed, one-directional flow valve in fluidic communication with said passageway.